It is an object of the invention to provide a technique in a power tool (101) having a detachable bit holder (137) for preventing a bit holder (137) from being detached from the tool body (103) even if unexpected external force is exerted on an operating member (271) for lock (169) release. A representative power tool (101) includes a tool body (103), a single holder mounting portion (139). The holder mounting portion (139) removably holds a bit holder (137) selected from multiple kinds of bit holders for holding multiple kinds of tool bits (119) in different manners. Each bit holder (137) includes a cylindrical portion (167), a through hole (167a) formed through the cylindrical portion (167), an engaging member (169) disposed within the through hole (167a), a cylindrical operating member (271) axially movably fitted on the cylindrical portion (167) between a movement prevented position and a movement allowed position. The operating member (271) is moved to the tool body (103) side in order to be switched from the movement prevented position to the movement allowed position so that the holder mounting portion (139) is allowed to be pulled out of the fitting hole (167b).